This research project is designed to investigate trends in fertility and migration in the Connecticut River Valley of Massachusetts. The sources of data include the historical and contemporary records available in the study area. This site has been selected because previous research has indicated that the records are well suited to the proposed problem and of considerable time depth. The emphasis of this project is on the interaction between demographic and genetic factors and causal agents in demographic transition. Vital records, census data, genealogical records and a variety of other sources are utilized for the estimation of fertility parameters. Fertility will be studied in relation to its historical decline and present-day manifestations. Migration will be studied primarily as it affects movements of individuals at marriage. The findings from the study area will be compared with those of other areas and populations to broaden the base upon which predictive statements can be made. A primary objective is to formulate models and hypotheses that have bearing on population planning in the United States and its Territories today.